Silicon carbide sinter and process for producing the same

Abstract

The present invention provides: a fabrication method of a silicon carbide sintered body, including a step of fabricating a mixed powder slurry by dissolving or dispersing silicon carbide powder, at least one organic material composed of a nitrogen source, and at least one organic material composed of a carbon source or carbon powder in a solvent, a step of fabricating a green body by pouring the mixed powder slurry into a mold and drying and a step of filling pores in the green body by immersing the green body in high purity metallic silicon that has been heated to 1450 to 1700° C. in a vacuum atmosphere or inert gas atmosphere and melted, and generating silicon carbide by reacting silicon sucked up into the pores in the green body by capillary action with free carbon in the green body; and a silicon carbide sintered body obtained by a reaction sintering method, having a density of 2.90 g/cm 3 or more and a volume resistivity of 10 0 Ω·cm or less, and containing nitrogen at 150 ppm or more.

What is claimed is:  
     
       1. A silicon carbide sintered body having a density of at least 2.90 g/cm 3  and a bending strength of at least 240 MPa, and containing at least 150 ppm of nitrogen and less than 10 ppm of an impurity element. 
     
     
       2. The silicon carbide sintered body of  claim 1 , fabricated by a reaction sintering method, said reaction sintering method comprising: 
       a step of fabricating mixed powder slurry by dissolving or dispersing silicon carbide powder, at least one organic material composed of a nitrogen source, and at least one of organic material composed of a carbon source or carbon powder in a solvent;  
       a step of fabricating a green body by pouring the mixed powder slurry into a mold and drying; and  
       a step of filling pores in the green body by immersing the green body in high purity metallic silicon that has been heated to 1450 to 1700° C. in a vacuum atmosphere or inert gas atmosphere and melted, and generating silicon carbide by reacting silicon sucked up into the pores in the green body by capillary action with free carbon in the green body.  
     
     
       3. The silicon carbide sintered body of  claim 1 , fabricated by a reaction sintering method, said reaction sintering method comprising: 
       a step of fabricating a silicon carbide powder containing nitrogen by dissolving a at least one silicon source containing a silicon compound, at least one carbon source containing an organic compound that generates carbon when heated, at least one organic material composed of a nitrogen source, and a polymerizing or crosslinking catalyst in a solvent, drying, and then sintering obtained powder in a non-oxidizing atmosphere;  
       a step of fabricating mixed powder slurry by dissolving or dispersing the silicon carbide powder containing nitrogen, and at least one of organic material composed of a carbon source or carbon powder in a solvent;  
       a step of fabricating a green body by pouring the mixed powder slurry into a mold and drying; and  
       a step of filling pores in the green body by immersing the green body in high purity silicon that has been heated to 1450 to 1700° C. in a vacuum atmosphere or inert gas atmosphere and melted, and generating silicon carbide by reacting silicon sucked up into pores in the green body by capillary action with free carbon in the green body.  
     
     
       4. The silicon carbide sintered body of  claim 1 , fabricated by a reaction sintering method, said reaction sintering method comprising: 
       a step of fabricating mixed powder slurry by dissolving or dispersing silicon carbide powder, at least one organic material composed of a nitrogen source, and at least one organic material composed of a carbon source or carbon powder in a solvent;  
       a step of fabricating a green body by pouring the mixed powder slurry into a mold and drying; and  
       a step of filling pores in the green body by immersing the green body in high purity metallic silicon that has been heated to 1450 to 1700° C. in a vacuum atmosphere or inert gas atmosphere and melted, and generating silicon carbide by reacting silicon sucked up into the pores in the green body by capillary action with free carbon in the green body.  
     
     
       5. The silicon carbide sintered body of  claim 1 , fabricated by a reaction sintering method, said reaction sintering method comprising: 
       a step of fabricating a silicon carbide powder containing nitrogen by dissolving a at least one silicon source containing a silicon compound, at least one carbon source containing an organic compound that generates carbon when heated, at least one organic material composed of a nitrogen source, and a polymerizing or crosslinking catalyst in a solvent, drying, and then sintering obtained powder in a non-oxidizing atmosphere;  
       a step of fabricating mixed powder slurry by dissolving or dispersing the silicon carbide powder containing nitrogen, and at least one organic material composed of a carbon source or carbon powder in a solvent;  
       a step of fabricating a green body by pouring the mixed powder slurry into a mold and drying; and  
       a step of filling pores in the green body by immersing the green body in high purity silicon that has been heated to 1450 to 1700° C. in a vacuum atmosphere or inert gas atmosphere and melted, and generating silicon carbide by reacting silicon sucked up into pores in the green body by capillary action with free carbon in the green body.  
     
     
       6. A fabrication method of a silicon carbide sintered body, comprising: 
       a step of fabricating mixed powder slurry by dissolving or dispersing silicon carbide powder, at least one organic material composed of a nitrogen source, and at least one organic material composed of a carbon source or carbon powder in a solvent;  
       a step of fabricating a green body by pouring the mixed powder slurry into a mold and drying; and  
       a step of filling pores in the green body by immersing the green body in high purity metallic silicon that has been heated to 1450 to 1700° C. in a vacuum atmosphere or inert gas atmosphere and melted, and generating silicon carbide by reacting silicon sucked up into the pores in the green body by capillary action with free carbon in the green body.  
     
     
       7. A fabrication method of a silicon carbide sintered body, comprising: 
       a step of fabricating a silicon carbide powder containing nitrogen by dissolving at least one silicon source containing a silicon compound, at least one carbon source containing an organic compound that generates carbon when heated, at least one organic material composed of a nitrogen source, and a polymerizing or crosslinking catalyst in a solvent, drying, and then sintering obtained powder in a non-oxidizing atmosphere;  
       a step of fabricating mixed powder slurry by dissolving or dispersing the silicon carbide powder containing nitrogen, and at least one organic material composed of a carbon source or carbon powder in a solvent;  
       a step of fabricating a green body by pouring the mixed powder slurry into a mold and drying; and  
       a step of filling pores in the green body by immersing the green body in high purity silicon that has been heated to 1450 to 1700° C. in a vacuum atmosphere or inert gas atmosphere and melted, and generating silicon carbide by reacting silicon sucked up into pores in the green body by capillary action with free carbon in the green body.